LintCode 448 : Inorder Successor in BST

Solution to Inorder Successor in BST Problem. Watch this video for explanation.

class Solution {
    public TreeNode inorderSuccessor(TreeNode root, TreeNode p) {
        if(root==null)
            return null;
     
        TreeNode parent = null;
        TreeNode current = root;
        while(current!=null && current.val!=p.val){
            if(current.val > p.val){
                parent = current;
                current = current.left;
            }else{
                current = current.right;
            }
        }
     
        if(current==null)        
            return null;
     
        if(current.right==null)
            return parent;
     
        current = current.right;
        while(current.left!=null)
            current = current.left;
     
        return current;
    }
}